Nebraska's Top Weed Problems and Most Common Herbicides
July 26, 2018

Stakeholders across Nebraska were surveyed during Nebraska Extension meetings about their top weed management issues. The survey was conducted at seven locations (Atkinson, Norfolk, Gering, Beatrice, Hastings, Kearney and North Platte) representing the four extension districts (Figure 1) in 2015.

A total of 425 responses (growers: 151, crop consultants: 113, and others: 161) were represented in the final survey report. Stakeholders were asked questions on four topics:

Crop Production and Problem Weeds

Herbicide Use

Glyphosate-Resistant Weed Management

Weed Management Research and Extension Priorities

Crop Production and Problem Weeds

Survey results showed that corn and soybean were the major crops in Nebraska. Less than 20% of the total area was planted with alfalfa, dry edible bean, grain sorghum, hay, proso millet, sugarbeet, and wheat. The greatest crop diversity was in the Panhandle district.

In Nebraska the most problematic weeds were common waterhemp, marestail, and kochia, followed by velvetleaf, common lambsquarters, Palmer amaranth, and giant ragweed.

Table 1. The top five problem weeds by Nebraska reporting district, based on a 2015 statewide survey.

Rank

Northeast

Panhandle

Southeast

West Central

1

Common waterhemp

Kochia

Common waterhemp

Kochia

2

Marestail

Common lambsquarters

Marestail

Common waterhemp

3

Velvetleaf

Field bindweed

Kochia

Marestail

4

Kochia

Palmer amaranth

Velvetleaf

Palmer amaranth

5

Giant ragweed

Canada thistle

Common lambsquarters

Foxtails

The majority of growers and crop consultants who responded were concerned about the evolution and spread of the ALS inhibitor-resistant (for example, Classic, Pursuit, and Sceptor) and glyphosate-resistant weeds, such as common waterhemp, marestail, kochia, Palmer amaranth, and giant ragweed. In this survey, 40%, 26%, 23%, and 11% of growers reported having no, one, two, and three or more glyphosate-resistant weed species, respectively, on their farm.

Herbicide Use

Respondents indicated that residual herbicides applied pre-emergence followed by post-emergence application of glyphosate tank-mixed with other herbicides was the most effective weed management option (Figure 2). Of the growers, 72% indicated using at least one pre-plant burndown herbicide in the spring. Glyphosate, 2,4-D, and Sharpen (saflufenacil) were the most commonly used pre-plant burndown herbicides listed in the survey.

Figure 2. Survey respondents indicated use of pre-emergence herbicide was higher in corn compared to soybean.

Table 2. The top three most commonly used pre-emergence herbicides in field corn, soybean, and grain sorghum, based on a 2015 statewide survey.

Rank

Field Corn

Soybean

Grain Sorghum

1

Lexar EZ/Lumax EZ

Authority First/Sonic

Bicep II Magnum

2

Corvus

Valor/Valor XLT

Lexar/Lumax

3

Degree Xtra/Harness Xtra / Keystone NXT

Enlite/Envive

Atrazine

The majority of corn and soybean acres were treated with glyphosate. Select Max was also listed among the most commonly used soybean post-emergence herbicides to control volunteer corn and other grass weeds.

Table 3. The top three most commonly used post-emergence herbicides in field corn, soybean, grain sorghum, and wheat, based on a 2015 survey.

Rank

Field Corn

Soybean

Grain Sorghum

Wheat

1

Glyphosate

Glyphosate

2,4-D

2,4-D

2

Halex GT

Cadet

Dicamba

Ally XP

3

Status

Select Max and Cobra

Huskie and Permit

Amber/Rave

Glyphosate-Resistant Weed Management

Growers and crop consultants reported that their average weed management cost in corn and soybean were $36 and $33 per acre, respectively. Cost of weed management for sugarbeet, which was only reported from the Panhandle District, was $43 per acre.

In this statewide survey, 80% of the respondents expressed their concerns regarding the volatility/physical drift of 2,4-D and dicamba following the commercialization of new crop technologies (Roundup Ready 2 Xtend and Enlist). However, misapplication of the herbicides, temperature inversion, tank contamination, and evolution of herbicide-resistant weeds were other concerns.

Weed Management Research and Extension Priorities

Herbicide-resistant weed management was identified by 48% of respondents as their top priority for research and extension. A variety of other topics, such as the development of new herbicide modes-of-action, integrated pest management, reducing off-target herbicide movement, cover crops, and farm safety were also listed as research and extension priorities.